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| Titel |
Global monitoring of terrestrial chlorophyll fluorescence from moderate-spectral-resolution near-infrared satellite measurements: methodology, simulations, and application to GOME-2 |
| VerfasserIn |
J. Joiner, L. Guanter, R. Lindstrot, M. Voigt, A. P. Vasilkov, E. M. Middleton, K. F. Huemmrich, Y. Yoshida, C. Frankenberg |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 6, no. 10 ; Nr. 6, no. 10 (2013-10-25), S.2803-2823 |
| Datensatznummer |
250085090
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| Publikation (Nr.) |
 copernicus.org/amt-6-2803-2013.pdf |
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| Zusammenfassung |
| Globally mapped terrestrial chlorophyll fluorescence retrievals are of
high interest because they can provide information on the functional
status of vegetation including light-use efficiency and global primary
productivity that can be used for global carbon cycle modeling and
agricultural applications. Previous satellite retrievals of
fluorescence have relied solely upon the filling-in of solar Fraunhofer lines
that are not significantly affected by atmospheric absorption.
Although these measurements provide near-global coverage
on a monthly basis, they suffer from relatively low precision and
sparse spatial sampling. Here, we describe a new methodology to
retrieve global far-red fluorescence information; we use hyperspectral
data with a simplified radiative transfer model to
disentangle the spectral signatures of three basic components:
atmospheric absorption, surface reflectance, and
fluorescence radiance. An empirically based principal
component analysis approach is employed, primarily using cloudy data over
ocean, to model and solve for the atmospheric absorption. Through
detailed simulations, we demonstrate the feasibility of the approach and show
that moderate-spectral-resolution measurements with a relatively high
signal-to-noise ratio can be used to retrieve far-red
fluorescence information with good precision
and accuracy. The method is then applied to data from the Global Ozone
Monitoring Instrument 2 (GOME-2). The GOME-2 fluorescence retrievals
display similar spatial structure as compared with those from
a simpler technique applied to the Greenhouse gases Observing
SATellite (GOSAT). GOME-2 enables global mapping of far-red fluorescence with higher precision
over smaller spatial and temporal scales than is possible with
GOSAT. Near-global coverage is provided within a few days. We are
able to show clearly for the first time physically plausible
variations in fluorescence over the course of a single month
at a spatial resolution of 0.5° × 0.5°. We also show some
significant differences between fluorescence and coincident
normalized difference vegetation indices (NDVI) retrievals. |
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